Critics say it does not reflect better service but rather the frustration of passengers so fed up they're not filing complaints. Congress is pushed to adopt a passenger bill of rights.

After hearing Jim Engle of Sierra Madre talk about the headaches he and his wife endured on a round trip from Burbank to Detroit on American Airlines in the summer, you might be surprised to hear that the country's airlines continue to get great marks in customer service.

Engle and his wife suffered through several delays, an unscheduled stop in Ontario and airline staff who, he said, were curt and unhelpful.

"And I don't have enough time to tell you about the extra charges for baggage and food and water, which ran out before half the plane was served," he complained.

Despite the experience of Engle and other passengers, the latest report from the U.S. Department of Transportation shows that complaints against airlines dropped nearly 12% in September compared with the same period last year and 32% from August 2009.

Even when the overall drop in passenger traffic is factored in, the complaint rate against the airlines is down to 0.88 complaints per 100,000 passenger flights this September from 0.99 complaints in September 2008.

Engle and other airline critics believe the reason for the drop in complaints does not reflect improved airline services but rather a growing frustration by passengers who are so fed up that they don't file complaints.

After all, Engle didn't file a complaint with American or the Department of Transportation.

"They're miserable and they are resigned that nothing is going to change," said Kate Hanni, founder of FlyersRights.org, a website that has been pushing Congress to adopt a passengers' bill of rights.

Hanni, who has become a vocal airline critic since she and her family were stuck on a plane for nine hours on a tarmac in Austin, Texas, in 2006, said her organization's complaint hotline -- (877) 359-3776 -- continues to get a steady stream of angry calls from frustrated airline passengers.

The complaints reported to the Department of Transportation come directly from airline passengers who either call the complaint line -- (202) 366-2220 -- write to the agency or file a complaint online at airconsumer.ost.dot.gov.

But they are not required to report general grievances about service, such as dirty seats, rude staff and excessive fees.

Hanni and other critics say it simply may appear that the airlines are doing a better job because of the deep drop in passenger traffic.

The Department of Transportation also reported improved on-time performances for the nation's largest airlines in September, when the on-time rate was 86.2%, compared with 84.9% in September 2008 and 79.7% in August 2009.

Airline experts say carriers have an easier time keeping flights on schedule because many have eliminated flights and grounded planes because of dropping demand. More-cooperative weather patterns this year also have kept airlines on schedule.

U.S. airlines also lost or mishandled less luggage: 3.01 bags per 1,000 passengers in September, compared with a rate of 3.86 in September 2008 and a rate of 4.04 in August 2009, according to the department report.

American Airlines spokesman Tim Smith acknowledged that improved weather and declining passenger traffic have helped airlines reduce flight delays, lost-luggage reports and other problems. But he attributed the overall drop in complaints at American to improved service.

He said American's internal data show that the number of passenger complaints has dropped 20% to 30% over last year. He points to a new airline effort to deploy customer service workers throughout the terminals to help passengers solve glitches with luggage and flight schedules.

As for Engle's nightmare trip to Detroit, Smith said the airline gets more complaints than compliments because people with a gripe are more vocal.

Still, he said, American continues to strive to resolve every complaint.

"We are not satisfied if the customers are not satisfied," he said.

The key component of the passengers' bill of rights supported by Hanni and other airline critics is a guideline for returning passengers to the terminal when a plane is delayed on the tarmac for more than three hours.

Tarmac delays are a major headache, but lately air travelers seem increasingly angry about the fees that airlines charge to check luggage and get a snack, a pillow or a drink.

Now an airline consulting firm has proposed another "passenger bill of rights" to protect travelers from hidden, excessive and unfair airline fees.

Airline Information, a Miami firm that organizes airline conferences and consults for the industry, has created an eight-point bill of rights for airline passengers who are the target of such a la carte fees.

Among the mandates of the bill:

* All fees must be transparent.

* Customers have a right to know the total cost of a flight, plus extra fees, before paying the fare.

* Customers have a right to a refund if they don't get the purchased a la carte services that were promised.

The bill of rights have been debated among airline representatives at conferences in Huntington Beach and London in the last three months.

Roger Williams, managing partner of Airline Information, said his company proposed the bill of rights because it was clear that such fees are a permanent part of the industry.

Unless the airlines manage the extra fees in a responsible manner, Williams said he fears that the federal government may impose regulations on such fees.

"We are trying to stay ahead of the curve," he said.

So far, no airlines have endorsed the airline fees bill of rights. But Williams said he hoped to get many airlines to agree to the guidelines by the end of the year.